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Janus kinase 2 Mutation, Qualitative

Item Value
Approval req'd? No
Available Stat? No
Utilization Guidelines Patients suspicious for chronic myeloproliferative disorders (PV, ET or PMF excluding CML), but having equivocal morphology and/or clinical picture. In cases suspected of PV, EPO level should be evaluated to rule out secondary erythrocytosis before JAK2 mutation test is considered; while, in cases suspicious for ET, serum iron and ferritin should be checked to rule out secondary thrombocytosis. The cases, which fulfill diagnostic criteria for PV or other MPD, are not indicated for this test because currently, JAK2 mutation has no prognostic significance and is not used as a minimal residual disease marker.

V617F is found in approximately 95% of patients with polycythemia vera. It is also found in approximately 50% of patients with essential thrombocytopenia (ET) or primary myelofibrosis (PMF). The detection of V617F complements histological findings aimed at the diagnosis of ET and PMF.

Tests with long turn-around times (ie. Molecular based tests and Microarrays) should only be requested on an inpatient if the result is going to affect the inpatient management.

If the patient will likely be discharged before the result will be available, the test should be requested after discharge. (NOTE: UCSF Medical Center is not reimbursed for inpatient testing).

An exception to the above may be appropriate if there is a possibility the patient will not survive to be discharged and the information is important for diagnosis and/or family decisions/management (ie. recurrence risk).
Test code JAK2
Test group JAK2
Performed by Medical Genomics - Molecular Diagnostics
In House Availability Run 2x per week, Tuesday & Thursday, day shift only
Method PCR and allele-specific hybridization
Collection Instructions Avoid hemolysis.

Due to stability issues these samples should only be collected Monday through noon Friday.

Do not collect sample in heparin. Keep sample refrigerated for overnight or longer storage.

For UCSF Samples (from remote sites) Click here for sample collection instructions

For NON-UCSF Samples Click here for Requisition form & Account set-up instructions. Note we only do institutional billing.
Container type Lavender top (3 mL)
Amount to Collect
Blood 3 mL
Bone marrow aspirate 1 mL
Sample type EDTA Whole blood or bone marrow aspirate
Preferred volume
Blood 3 mL
Bone marrow aspirate 1 mL
Min. Volume
Blood 1 mL
Bone marrow aspirate 0.4 mL
UCSF Rejection Criteria Heparinized sample submitted. Samples collected outside of stated time frames.
Processing notes Do not centrifuge. Refrigerate sample but do not freeze. Ship refrigerated.
Normal range Negative
Synonyms V617F; Myeloproliferative disorders; MPD; JAK2
Stability Room temperature 3 days, refrigerated 3 days, frozen at -20C Unacceptable.
Turn around times 7-10 days
Additional information An interpretation of this test by a laboratory physician will automatically be performed and billed for separately.

Clinical Significance:
A somatic mutation in a highly conserved residue of the Janus kinase (JAK2) on chromosome 9 was detected in 80% of patients with polycythemia vera(PV), and 30-50% of patients with essential thrombocythemia (ET) or primary myelofibrosis (PMF). This point mutation in exon 14 of JAK2 alters codon 617 from a valine to a phenylalanine residue on JH2 domain of JAK2 kinase, thus disrupting auto-inhibitory property of this pseudokinase domain and leading to constitutive activation of the tyrosine kinase. This enhanced JAK2 kinase activity is thought to confer erythropoietin hypersensitivity and erythropoietin independent survival to the myeloid stem cells. Although JAK2 V617F mutation has been detected in variable percentage of patients with other type of myeloid malignancies, normal individuals tested so far are exclusively negative for the mutation.

This assay has 1% DNA sensitivity of the JAK2 V617F mutation in a background of 99% DNA without the mutation. A positive result is strongly supportive of a diagnosis of PV, ET or CIMF.

A negative result does not rule out the presence of V617F at a level below the sensitivity of this assay and does not exclude the presence of other mutations in the JAK2 gene.

This test was developed and its performance characteristics determined by the UCSF Clinical Laboratories. It has not been cleared or approved by the U.S. Food and Drug Administration. The FDA has determined that such clearance or approval is not necessary. Performance characteristics refer to the analytical performance of the test.
CPT coding 81270
LOINC code 48726-4
LDT or Mod FDA? Yes
Last Updated 5/26/2015 8:46:39 AM
Entry Number 1100
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